The present invention relates to a microprocessor arrangement for use in a complex vehicle control system which includes a plurality of microprocessor systems that are linked by bus systems and perform at least anti-lock control (ABS) and/or traction slip control (ASR) and at least one other high-computation control function, such as yaw torque control (GMR), and monitoring functions, the microprocessor systems including the conditioning of input signals.
Electronic control systems for automotive vehicles become more and more important which relieve the work of the driver and enhance safety and driving stability. This applies, above all, to anti-lock systems (ABS), traction slip control systems (ASR), systems for the electronic control of brake force distribution (EBV), etc. Most recent developments include yaw torque control and driving stability control (GMR and FSR). These are only some examples. Combining a plurality of control systems in a compound unit is also known in the art.
To achieve complex control objectives, microprocessor structures of most different types are employed nowadays. For example, German patent No. 32 34 637 discloses an ABS system with a controller which has two (or more) parallel operating microcontrollers to produce braking pressure control signals. These microcontrollers process like input signals pursuant to an identical computer program. The output signals and, if necessary, also internal signals of the microcontrollers are monitored for coincidence to detect malfunctions in any one of the two controllers. In the event of non-coincidence of the signals which are redundantly processed in the microcontrollers, the electronic control is disconnected to ensure that at least braking without control remains possible.
Further, German patent application No. 41 37 124 discloses a circuit arrangement of this type which has a so-called asymmetrical redundance. The input signals, i.e. the signals produced by wheel sensors and representing the rotational behavior of the wheels, are sent to two parallel microcontrollers, as in the above-mentioned case. However, only one of the two microcontrollers performs the complete control program, while the second microcontroller reproduces the control philosophy in a simplified form or, rather, processes the input signals by way of simplified algorithms, as compared to the main microcontroller. Comparison of the output signals of both microcontrollers will then permit identifying, despite the simplified processing in one of the two microcontrollers, whether data processing is faulty or correct.
When an automotive vehicle control system, for example an ABS/ASR system, is extended by a high-computation driving stability control system (FSR or GMR), it is principally possible to additionally install a complete control system which also includes safety functions. The advantage is that the individual components, i.e., both the previous ABS/ASR system and the driving stability control system, are independent of each other, and that only the affected component will fail when defects or malfunctions occur.
It would, principally, also be possible in a basic structure (ABS/ASR) that is extended by driving stability control to include the additional calculating operations, including the monitoring functions, in the processor structure when microprocessor systems of a sufficient capacity are provided. However, there is the shortcoming that the overall system would have to be disconnected when a defect occurs in one component. Because an overall system of this type is comparatively complex and sophisticated, the occurrence of malfunctions is relatively likely.